With the development of technologies, mobile communication terminals (such as cell phones, tablet computers, and so on) have had very broad applications now.
Because mobile communication terminals are all powered by batteries, their continuous service time is limited. When the battery is used up, it has to be charged. However, frequent charging operations affect the user's normal usage. If the user forgets to charge the device, the problem that the device is not usable may be caused.
In particular, with the popularization of smart phones, the above problems become more notable. Because the smart phones have larger power consumption though they have more functions, while the energy storage capacity of batteries cannot be increased unlimitedly, the smart phones have shorter continuous service time. Usually, many smart phones need to be charged every one or two days, which degrades users' usage experience dramatically.